The present invention relates to a capacitor ignition system for internal-combustion engines. More particularly, the present invention relates to a capacitor ignition system for an internal-combustion engine of the type including a direct voltage converter, having a control circuit coupled therewith, for cyclically charging the storage capacitor, a switch-through circuit for discharging the capacitor in dependence of the firing order for the engine and a firing circuit to which the discharge voltage is fed for generating the ignition voltage for the spark path of the spark plugs.
With such ignition systems with capacitive energy storage it is always possible, in part independently of the position of the breaker points of the firing circuit, to have available the full ignition voltage at high rise speeds, and with suitable selection of the capacitor it is also possible to generate high peak current intensities. Thus in every case high energy ignition sparks are formed between the electrodes of the spark plugs. Due to the configuration of the known systems, however, the ignition energy from the storage capacitor is used largely to form the so-called ignition spark head, i.e., to initiate the ionization of the spark path, so that it is not always assured that sufficient energy is available in the storage capacitor for the so-called post discharge, which is necessary following the ionization during the corresponding period of dwell of the spark and which also requires high energy. Due to the applicable physical laws for the capacitor discharge, devices in which all of the ignition energy is furnished by one storage capacitor do not meet all requirements during use.
Capacitor ignition systems are known in which each storage capacitor is charged by one charging pulse in that, the primary coil of a transformer connected between the control circuit and the ignition circuit is connected via a semiconductor switching device with the battery in the respective firing order (Elektronik 1968, Issue No. 8, page 239). Thus every charging process is dependent on the voltage supply so that with a low battery voltage optimum firing behavior is not assured.
Ignition systems of the above-mentioned type are also known in which although the storage capacitor is charged independently of the battery voltage, there is not always sufficient firing energy available for the post discharge (Elektronik 1966, Issue No. 7, pages 201 et seq.).
In order to overcome this drawback, an ignition system has become known in which the energy of the storage capacitor is intended to ionize the spark path, and the energy for the post discharge is obtained directly from the battery (Elektronik 1976, Issue No. 1, pages 61 et seq.). In this circuit the duration of the supply of energy from the battery is coupled with the switching period of a flip-flop stage in the control circuit and with the magnetization of the blocking oscillator type direct voltage converter of the circuit, so that a sufficient period of dwell for the ignition spark is not assured in all cases. Moreover, the storage capacitor is charged each time only with one charging pulse so that it is questionable whether the firing energy is always available in sufficient quantities under the various conditions of use.